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RE:Red color



>Richard,
>
>VERY interesting. The P&A bulb and the C50 bulb have very similar outputs
>when expressed in PAR units (total number of photons emitted in between 400 
>and 700 nanometers). But the P&A creates about 35% MORE red photons than the 
>C50, and about 35% LESS blue photons than the C50. So is this evidence that
>an excess of red photons stimulates the red color in plants ? Maybe this
>is why some of my formerly redder plants turned out to greener growth when 
>I replaced a 1:1 mix of C50 and GroLux (60 watt total) with a mix of 5400K 
>and 6700K PCs (110 watt total). This increased the total number of PAR photons 
>by 120%, but  dramatically shifted the red/blue ratio from 1.7 to 0.6. Hummm....
>
>-Ivo Busko
> Baltimore, MD

I think you might consider trying that with several different plants of red
color. Ludwigia inciliata and granulosus do great at 3050k color temps. At
5500 or 6700 not so well. In many many cases plants do better at these lower
(redder) color temps. So do most every plant except Rotala macrandra wide
leaf. Stable conditions(trace/macro elements-CO2 etc) need to prevail before
assuming it's the light only. 

The best way I've come up with for testing a light source is using  a 2foot
bank of lights on a 4 foot tank and comparing them to a another 2 foot light
on the other side of the same tank. This makes all the conditions the same
except for the light. 

There are many factors to consider before drawing a conclusion on red color.
Can you turn a plant green to red and red to green for instance? Is it low
Phosphorus or is it high sugar content in the leaves?Is it lighting or is it
a balance of all these factors?
Isolation is going to be *very difficult* to be certain. Each plant may need
case by case treatment too.
Generally speaking, lower amounts of lighting(2 watts a gallon with FL's a
mix of a white cheapy and aquarium bulb such as a triton/vita etc), cooler
temps, good well balanced tanks,
have seemed to have better reds in them. There are many exceptions though.
Very hard to generalize. Would be nice though<g>!
Regards, 
Tom Barr